Sensitive Ecosystem Assessment and ROV Exploration of Reef (SeaRover) Synthesis Report 2020 MERC Consultants environmental and conservation services Dive 696 - 19-08-2019. Description: Rich geogenic reefs including mud, pebble field and boulders hosting various and abundant epifauna. -12.07757983, 51.54346883, -1255.5 m. 2 MERC Consultants: SeaRover Survey Synthesis 2021 Sensitive Ecosystem Assessment and ROV Exploration of Reef (SeaRover) Synthesis Report, January 2021 Authors Bernard Picton, Christine Morrow, Louise Scally & Nick Pfeiffer Commissioned by Marine Institute, Rinville, Oranmore, Co Galway Acknowledgements The authors would like to thank Fergal McGrath and David O’Sullivan (INFOMAR, Marine Institute) for support and advice over the course of this project and for the supply of data. Prof. Louise Allcock (NUI Galway) shared standard operating procedures and Dr Kerry Howell (University of Plymouth) advised on the analysis of data. This work was commissioned as part of extensive offshore reef survey of Ireland’s Northwest Continental margin delivered by the Marine Institute in partnership with the National Parks and Wildlife Service (NPWS), funded by the European Maritime and Fisheries Fund (EMFF), and coordinated and led by INFOMAR (Integrated Mapping for Sustainable Development of Ireland’s Marine Resources). Citation: Picton, B.E., Morrow, C.C., Scally, L. & Pfeiffer, N., 2021. Sensitive Ecosystem Assessment and ROV Exploration of Reef (SeaRover), Synthesis Report. Report prepared by MERC Consultants Ltd. on behalf of the Marine Institute, Galway 161 pp. 3 Executive Summary A requirement exists to quantify the abundance and distribution of offshore biogenic and geogenic reef habitats in Irish waters to fulfil Ireland’s legal mandate and to generate baseline data from which appropriate monitoring systems can be established. To address this an extensive offshore reef survey of Ireland’s continental slope was commissioned by the Marine Institute in partnership with the National Parks and Wildlife Service (NPWS), funded by the European Maritime and Fisheries Fund (EMFF), and coordinated and led by INFOMAR (Integrated Mapping for the Sustainable Development of Ireland’s Marine Resources). The objectives of the survey were to implement the EMFF’s Marine Biodiversity Scheme - Natura Fisheries, by mapping offshore reef habitats with a view to protecting them from deterioration due to fishing pressures. The reef project aligns with sub-article 6.2 of the Habitats Directive (EC 92/43/EEC) which requires member states to take measures to avoid deterioration of protected habitats. The Sensitive Ecosystem Assessment and ROV Exploration of Reef (SeaRover) survey took place between 2017 to 2019. The 2017 and 2018 surveys took place onboard the ILV Granuaile whilst the third survey leg in 2019 employed the Marine Institute’s RV Celtic Explorer. The Marine Institute’s remotely operated vehicle (ROV) Holland I was used for each of these cruises. The Holland I was equipped with a high-definition (HD) camera, various composite video feeds and a robotic arm for sample collection. The primary aim of the survey was to map the distribution and abundance of biogenic and geogenic reef habitat along Ireland’s continental margin using HD video. Survey transects were pre-selected following a consultation process between the Marine Institute and the National Parks and Wildlife Service. Selection criteria included depth range, areas of highly sloping terrain, geographical spatial discreteness, historical fishing activity, historical scientific studies and the presence or absence of certain target geomorphological features which included, canyons and canyon walls, gullies, escarpments, ridges, carbonate mounds and cobble fields. A total of 154 transects were surveyed, the locations of the transects are shown in Figure 16. The findings of the SeaRover survey will contribute to the establishment of site specific conservation objectives for the offshore Special Areas of Conservation (SAC) for NPWS. The survey recorded 553 Vulnerable Marine Ecosystems (VMEs) (Table 7). The locations of these VMES are shown in Figure 75. The findings will contribute to the Department of Agriculture, Food and Marine (DAFM) obligation to map Ireland’s vulnerable fisheries resources. SeaRover surveyed just the continental slope and not the extensive areas of level seabed making up the continental shelf, nor the abyssal seabed below -3000 m depth, nor the Rockall Bank outside Ireland’s Exclusive Economic Zone (EEZ) but within Ireland’s continental shelf territory. Ireland’s area of continental slope targeted by SeaRover (-540 to -2600 m depth) was calculated as approximately 94456 km2, SeaRover surveyed 0.91 km2 which is 0.00096% of this area. This is an indication of the amount of Ireland’s offshore area that remains relatively unexplored. The survey data acquired improves our understanding of the distribution and ecological requirements for these vulnerable ecosystems and can be used in combination with detailed bathymetric data to predict the likely extent of these ecosystems and help support the sustainable management of Ireland’s valuable and vulnerable marine resources. The survey data establishes the need to build on what has been collected to date, and in conjunction with detailed bathymetric data, will help target future mapping of reef habitat. The SeaRover data will ensure the availability of comprehensive biological baseline datasets which will be critical to the formulation of future policy on the management, monitoring and conservation of Ireland’s deep- water ecosystems. Below is a summary of the main findings of the SeaRover Survey. Occurrence of Coldwater Reef/Non-reef • 89 dives (58%) encountered reef habitats • 78 dives encountered geogenic reef • 47 dives encountered biogenic reef • 65 dive sites (42%) hosted neither biogenic nor geogenic reef. 4 MERC Consultants: SeaRover Survey Synthesis 2021 Diversity 491 putative species were identified from HD video footage supplemented by high resolution imagery (using an operational taxonomic unit (OTU) system as it is often not possible to identify fauna to species level) • Dive 488/Transect 20 was the most diverse with 137 OTUs • 49 OTUs were identified on the average dive • Only 7 OTUs were found in more than half of the transects • 65 OTUs were found in only one transect Biotopes 139 biotopes and potential biotopes were identified in line with the Marine Habitat Classification for Britain and Ireland (MHCBI, v.15.03), of which: • 85 are existing biotopes, un-altered from the MHCBI listing • 10 are minor variants of existing biotopes • 44 are potential new biotopes, or variants which may warrant becoming new child biotopes Conservation targets 147 dives encountered conservation listed habitats, being either an International Council for the Exploration of the Sea (ICES) Vulnerable Marine Ecosystem, and/or an OSPAR Threatened and/or Declining Habitat • 111 Mud & sand emergent fauna • 69 Coral gardens • 17 Deep sea sponge aggregations • 35 Coral reefs • 35 dives encountered conservation listed species (ICES/IUCN) Two conservation listed species were encountered repeatedly: • 26 dives encountered Hoplostethus atlanticus (Orange Roughy) including one dive where they were aggregated and abundant (D464B/T18) • 17 dives encountered Centrophorus squamosus (Leafscale Gulper Shark) Seabed Pressures The SeaRover survey recorded the presence and category of marine litter. The majority of non-fishing gear and fishing gear was found in the NW sector of the continental slope. The most commonly recorded gear was nylon gill nets and long lines, but trawl nets were also observed. On the continental slope adjacent to Ireland the SeaRover survey covered approximately 0.76 km2 of seabed, this area between -540 to -2600 m was calculated to be 88267 km2 (just over 0.0009% was surveyed visually by SeaRover)(Table 6). SeaRover observed discarded fishing gear on 42 dives within this area. Based on these figures, if the entire area of the continental slope was surveyed it is estimated that there would be more than 4 million encounters with lost fishing gear. Testing predictive models for coral and sponge distribution The SeaRover survey collected data to ground truth published models of habitat suitability for Lophelia reef and the bird’s nest glass sponge Pheronema carpenteri (Ross & Howell, 2013). The models’ predicted distribution was shown relative to where they were recorded by SeaRover. The model was mostly accurate at predicting the distribution of the cold water coral Lophelia. The ground truthing of the bird’s nest glass sponge Pheronema carpenteri gave more mixed results. Whilst Pheronema was recorded at two of the predicted sites, it wasn’t observed at two of the sites where it was predicted to occur and was present at a number of sites where the model had not predicted it. 5 Observations of note for the individual cruises 2017 The pigtail coral, Radicipes cf gracilis, has only rarely been recorded in the Rockall Trough, but was encountered on 7 SeaRover dives, and was twice encountered in loose aggregations (D467/T22, D469/T23). Solenosmilia variabilis reefs were encountered as deep as 1757m (on D458/T43). The community found on D453/T5 included many species that were either not encountered again, or that were found only rarely on other dives (e.g. the bamboo coral Keratoisis sp. OTU1157 (a fine, branched morphotype), was common on this dive but never encountered again). This dive offered the most unique community,